Categories

Statistics

View count:

73,185

Likes:

362

Dislikes:

56

Comments:

23

Duration:

03:47

Uploaded:

2015-07-03

Last sync:

2019-06-12 18:50

The world changes. It really does! But sometimes it changes so slowly that we don't notice it. Other times it changes REALLY FAST!!! In this episode of Crash Course Kids, Sabrina talks about some of the reasons things can change quickly or slowly.

This first series is based on 5th grade science. We're super excited and hope you enjoy Crash Course Kids!

///Standards Used in This Video///
5-ESS2-1. Develop a model using an example to describe ways the geosphere, biosphere, hydrosphere, and/or atmosphere interact. [Clarification Statement: Examples could include the influence of the ocean on ecosystems, landform shape, and climate; the influence of the atmosphere on landforms and ecosystems through weather and climate; and the influence of mountain ranges on winds and clouds in the atmosphere. The geosphere, hydrosphere, atmosphere, and biosphere are each a system.] [Assessment Boundary: Assessment is limited to the interactions of two systems at a time.]

Introduction

I love change. It gives me something to look forward to. A new book to read, a new flavor of ice cream to try, or a snazzy new pair of specs. If it's new and different, I say bring it.

And if you think about it, change is all around us. Seasons change as the Earth travels around the Sun, clouds in the sky change shape, the ground beneath our feet is constantly moving. That's right the Earth's geosphere, as stationary as it seems, is actually moving. And because of all of this, all of the landforms, that is the features of the Earth's surface like mountains and deserts, are constantly changing. Alrighty then. But how? How to landforms form and change over time?

Big Question

Well the first thing you need to know is that the top-most layers of the Earth are made up of plates. Despite their name, these are nothing like dinner plates. You can think of them as big, thick pieces of soil and rock, and I mean big. The North American plate covers all of North America plus Greenland and parts or Northern Asia, and these parts are moving slowly. So slowly in fact, that we don't even notice them moving. The plates cruise along at about 2 to 5 centimeters a year, which is about as fast as your fingernails grow.

These plates can move away from each other, toward each other, or even slide over top one another, and sometimes their movement causes landforms to change. But landforms can also change slowly in other ways, through things like erosion and weathering. You already know that these are powerful forces that change rock through the effects of wind, water, and ice.

Investigation

For example, the Grand Canyon in Arizona was formed by the Colorado River and other forms of water slicing through a plateau of rock through erosion over many, many, many years. If you're the impatient sort though, have I got news for you. Sometimes, landforms can change quickly. I mean really quickly, as in within a few minutes. So let's take a look at different ways that landforms can change by exploring a couple of particularly famous examples.

Let's start with one of nature's most famous quick changes. A volcano in the Pacific Northwest of the United States called Mount St. Helens did some serious landform rearrangement in May of 1980. The surface of the Earth went from this, to this in a matter of minutes. The force of the eruption caused the largest landslide in history, which changed even more the way the land looked, and still looks today all around the mountain.

But most landforms change much more gradually, and by gradually I mean so slowly that we don't even notice them changing at all. The Grand Canyon is a great example of this, but it's not the only one. In the early 1800's, a group of explorers stumbled across a really cool rock formation in the White Mountains of New Hampshire. Because the shape of the landform looked like the profile of an old man, it was nicknamed "The Old Man of the Mountain". Geologists think that this old man was probably created through erosion by glaciers - big, slowly moving sheets of ice - over 200 million years ago, and there the old man stayed, exposed to wind and snow and ice. In other words, weathering and more erosion.

He looked pretty much the same for millions of years, until 2003 when finally the whole formation tumbled off the side of the mountain. The Old Man of the Mountain is a great example of how landforms are both created and continuously changed in ways we don't even notice... until we notice them.

Conclusion

So, now maybe you know what I mean when I say that the Earth is always changing. Landforms as we know them won't look the same forever because these features on the Earth's surface can change over time. They can change quickly like when a volcano erupts, or they can change slowly through processes like weathering and erosion, when wind and water change the shape of mountains, or cause canyons to form - and that's totally fine with me. I can always go for a change of scenery.